FIGS. 1A and 1B show the structure of the connector disclosed in U.S. Patent Application Publication No. 2011/0003501A. The reference numeral 11 in FIGS. 1A and 1B indicates an optical connector attached to an end of each of optical fibers and the reference numeral 12 indicates a counterpart optical connector to which the optical connector 11 is connected. The reference numeral 13 indicates a plug that houses the optical connector 11. The reference numeral 14 indicates a receptacle that houses the optical connector 12. The plug 13 and the receptacle 14 form the outer shells of the optical connectors 11 and 12, respectively. In FIGS. 1A and 1B, the reference numeral 15 indicates an optical cable and the reference numeral 16 indicates a transceiver to which the optical connector 12 is connected.
The receptacle 14 includes a hollow cylinder 17 and a flange 18 formed at one end of the hollow cylinder 17. Threads are formed in an outer circumference of the hollow cylinder 17 and depressions 19 are formed at two positions on an inner surface of the hollow cylinder 17.
The plug 13 includes a cylindrical body 21 and an external cylinder 22, which is placed external to the cylindrical body 21. Two boom-like arms 23 project from the cylindrical body 21. A retaining section 24 is provided at an end of each of the arms 23.
The plug 13 and the receptacle 14 are connected to each other when threads formed in an inner circumference at an end of the external cylinder 22 of the plug 13 are screwed onto the threads of the hollow cylinder 17 of the receptacle 14. At this time, the retaining sections 24 provided at the ends of the two arms 23 of the plug 13 are inserted into and caught in the depressions 19 of the hollow cylinder 17 of the receptacle 14.
In the above structure including the plug 13 and the receptacle 14, when the retaining sections 24 at the ends of the arms 23 of the plug 13 are caught in the receptacle 14, the arms 23 of the plug 13 can be retained to the receptacle 14 (that is, the plug 13 can be temporarily retained to the receptacle 14), thereby facilitating the connection of the optical connectors 11 and 12. Even when, for example, the receptacle 14 is attached to the ceiling etc. of a room and the plug 13 is connected to the receptacle 14 in a vertically upward direction, it is possible to prevent the optical connector 11 or the external cylinder 22 from being detached (falling) during insertion and connection of the optical connector 11 or screwing of the external cylinder 22.
A problem with the plug 13 shown in FIG. 1B is that a retaining strength is insufficient, so the retaining sections 24 are likely to be disconnected from the receptacle 14 when an external force is applied specially in the upward/downward direction (Z-direction), which is orthogonal to the left/right direction (Y-direction), in which the retaining sections 24 face each other, because the number of retaining sections 24 that face each other in the hollow cylinder 17 of the receptacle 14 is two, the retaining sections 24 are retained only by being caught in the receptacle 14, and the arms 23 are too long.